Nivea dos Santos got her first job as a live-in maid at age 12, dusting, vacuuming, ironing and polishing the silver of a wealthy Rio de Janeiro family from dawn until she'd fall, exhausted, into bed. More than two decades later, Brazil has passed legislation aimed at preventing such abuses.

The landmark domestic workers law, passed as a constitutional amendment last year and strengthened this month, aims to extend some of Brazil's generous labor protections to the more than 6 million maids, nannies, eldercare givers, gardeners and caretakers who work in privates homes - many toiling long hours for little or, in some cases, no pay.

For some, it's been a boon. Live-in nanny Eliane Soares Lemes said she would have left domestic work if it weren't for the legislation. After decades of working off the books, the 34-year-old was legally registered for the first time - meaning she now enjoys benefits such as paid transportation to and from work, paid vacation days and an annual "13th month" pay bonus that have long been sacrosanct for other Brazilian workers.

For others, such as dos Santos, it has meant the loss of a job, because her employer balked at having to limit work days to eight hours or shell out overtime pay.

"After seven years working in his home, my boss at the time told me he wasn't going to comply with the new law and he let me go me, just like that," said the 35-year-old mother of three.

The full impact of the law is hard to measure because informal work is not reported to the government, but experts estimate 300,000 domestic workers have lost their jobs as a result of the legislation, said Mario Avelino, who heads the Rio-based Instituto Domestica Legal, a nonprofit that lobbies for increased legal protection for maids.

Nevertheless, Avelino hails the law as a great advance.

"It challenged the culture of slavery that persists here in Brazil, inside people's homes," he said. "There's always been this acceptance that if a person works in your home, they somehow don't deserve the same rights that all other workers in Brazil have."

Pay for live-in domestic workers ranges roughly from $320 to around $700 a month in Rio, although Avelino estimates that nationwide some 35,000 domestic workers are still in conditions of semi-slavery, laboring for room and board but little or no pay.